diff --git a/package-lock.json b/package-lock.json
index ae1633b..1b6c65b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@apiture/openapi-down-convert",
-  "version": "0.12.0",
+  "version": "0.13.0",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@apiture/openapi-down-convert",
-      "version": "0.11.0",
+      "version": "0.13.0",
       "license": "ISC",
       "dependencies": {
         "commander": "^9.4.1",
diff --git a/package.json b/package.json
index f2ef482..072a3b4 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@apiture/openapi-down-convert",
-  "version": "0.12.0",
+  "version": "0.13.0",
   "description": "Tool to down convert OpenAPI 3.1 to OpenAPI 3.0",
   "main": "lib/src/index.js",
   "bin": {
diff --git a/src/converter.ts b/src/converter.ts
index d72013a..07c3358 100644
--- a/src/converter.ts
+++ b/src/converter.ts
@@ -251,7 +251,7 @@ export class Converter {
     }
   }
   removeUnsupportedSchemaKeywords() {
-    const keywordsToRemove = ['$id', '$schema', 'unevaluatedProperties', 'contentMediaType'];
+    const keywordsToRemove = ['$id', '$schema', 'unevaluatedProperties', 'contentMediaType', 'patternProperties'];
     const schemaVisitor: SchemaVisitor = (schema: SchemaObject): SchemaObject => {
       keywordsToRemove.forEach((key) => {
         if (schema.hasOwnProperty(key)) {
diff --git a/test/converter.spec.ts b/test/converter.spec.ts
index 8746255..0b2f582 100644
--- a/test/converter.spec.ts
+++ b/test/converter.spec.ts
@@ -355,6 +355,55 @@ describe('resolver test suite', () => {
     done();
   });
 
+
+  test('Remove patternProperties keywords', (done) => {
+    const input = {
+      openapi: '3.1.0',
+      components: {
+        schemas: {
+          a: {
+            type: 'object',
+            properties: {
+                  s: {
+                    type: 'string',
+                  },
+            },
+            patternProperties: {
+            "^[a-z{2}-[A-Z]{2,3}]$": {
+                type: 'object',
+                unevaluatedProperties: false,
+                properties: {
+                  t: {
+                    type: 'string',
+                  },
+                },
+              },
+            },
+          },
+        },
+      },
+    };
+    const expected = {
+      openapi: '3.0.3',
+      components: {
+        schemas: {
+          a: {
+            type: 'object',
+            properties: {
+              s: {
+                type: 'string',
+              },
+            },
+          },
+        },
+      },
+    };
+    const converter = new Converter(input, { verbose: true });
+    const converted: any = converter.convert();
+    expect(converted).toEqual(expected);
+    done();
+  });
+
   test('Remove contentMediaType keywords', (done) => {
     const input = {
       openapi: '3.1.0',